laborious中文意思是什麼

At the beginning of 20 century, midi boots with bootlace were becoming prevalent in us. whitcomb judson, a retired fat football player had to spend much time in putting on his boots every morning. to ease the laborious work, he managed to invent a zip - fastener, which allowed him to put on his shoes just in a few seconds. this is the naissance of zipper in the world